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COMMUNICATION
Journal Name
For dehydrogenation, TPD-MS results (Figure S5a) show that the Talents Program (XLYC1807157), and K. C. WoVnigew AErdticulecaOtniloinne
as-prepared sodium cyclohexylamide dehydrogenates at the Foundation (GJTD-2018-06). A. Wu acknDoOwIl:e1d0g.1e0s39t/hCe9CfCin0a8n59c3iaAl
temperature higher than 130 °C. Meanwhile, small amounts of by- support from the National Science Foundation of China (21773193).
products are detected during heating, indicating that side reactions
occurred. Then, a commercial 5% Rh/Al2O3 catalyst was employed to
catalyse the dehydrogenation of sodium cyclohexylamide.
Interestingly, the Rh-catalyzed sodium cyclohexylamide sample
starts to evolve H2 at about 80 °C and gives a broad desorption peak
Notes and references
centered at ca. 155 °C as shown in Figure S5b, which is much lower
than that of the pristine sodium cyclohexylamide. Further increasing
the temperature to 300 °C, more hydrogen can be released, which
may be due to the decomposition of the reactant. In order to
suppress the side reaction, catalytic dehydrogenation was conducted
at 150 °C which is below the temperature for producing those by-
products. As shown in Table 2, the conversion of sodium
cyclohexylamide dehydrogenation can be achieved as high as 99% in
11 hours. The selectivity to the desired product of sodium anilinide
was determined as 80%, whereas, 20% of by-product, N-
cyclohexylbenzenamine (NCHBA) was also observed (Figure S6).
Catalytic dehydrogenation is always a challenging task in organic
hydrogen carriers. Design and fabrication of novel catalyst will be
beneficial to the conversion and selectivity. Therefore, development
of efficient catalysts is highly demanded in the following
investigations.
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6. A. Züttel, P. Wenger, S. Rentsch, P. Sudan, P. Mauron and C.
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7. A. Gutowska, L. Li, Y. Shin, C. M. Wang, X. S. Li, J. C. Linehan, R.
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50, 74-85.
Nevertheless, the hydrogen uptake and release can be achieved
through the sodium anilinide-cyclohexylamide pair at the
temperature as low as 150 °C. It should be noted that the dimer by-
products (dicyclohexylamine or N-cyclohexylbenzenamine) were
always been observed during hydrogenation or dehydrogenation
(Table 1 and 2). Usually, the dimers were detected in the catalytic
12. D. Teichmann, W. Arlt, P. Wasserscheid and R. Freymann,
Energy Environ. Sci., 2011, 4, 2767-2773.
hydrogenation of aniline22. Therefore, the formation of dimers in our 13. E. Clot, O. Eisenstein and R. H. Crabtree, Chem. Commun., 2007,
22,2231-2233.
case may undergo
a similar pathway to that of catalytic
14. G. P. Pez, A. R. Scott, A. C. Cooper, H. Cheng, F. C. Wilhelm and
A. H. Abdourazak, Patent, 2008, US7351395.
15. R. H. Crabtree, Energy Environ. Sci., 2008, 1, 134-138.
16. K. Müller, J. Völkl and W. Arlt, Energy Technology, 2013, 1, 20-
24.
hydrogenation of aniline (Scheme S1 and S2).
In summary, the thermodynamics of aniline-cyclohexylamine pair
for hydrogen storage can be manipulated via metallation strategy,
i.e., the ΔHd of cyclohexylamides correlates well with the
electronegativity of metals. Specifically, sodium anilinide-
cyclohexylamide pair with ΔHd of 42.2 kJ/mol-H2 was successfully
synthesized. The hydrogenation and dehydrogenation can be
realized at the temperature as low as 150 °C in the presence of
commercial catalysts. More importantly, because of the large
diversity of organic compounds, it could be easily broadening the
current scope of amine-based materials thus providing vast
opportunities for the further exploration.
17. Y. Cui, S. Kwok, A. Bucholtz, B. Davis, R. A. Whitney and P. G.
Jessop, New J. Chem., 2008, 32, 1027-1037.
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Angew. Chem. Int. Ed., 2019, 58, 3102-3107.
19. J. Wu, I. Ying Zhang and X. Xu, ChemPhysChem, 2010, 11, 2561-
2567.
20. Based on liquid-phase values of ΔfH0 (C6H7N, l) = 31.3 kJ/mol and
ΔfH0 (C6H13N, l) = -147.7 kJ/mol.
21. Unpublished data. The synthesis of Na-Ru/TiO2 catalyst can be
found in experimental part.
22. H. Greenfield, J. Org. Chem., 1964, 29, 3082-3084.
Conflicts of interest
There are no conflicts to declare.
Acknowledgment
T. He and P. Chen acknowledge the supports provided by National
Key R&D Program of China (2018YFB1502100), the National Natural
Science Foundation of China (51671178, 21875246), Dalian Institute
of Chemical Physics (DICP DCLS201701), LiaoNing Revitalization
4 | J. Name., 2012, 00, 1-3
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